/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/* $FreeBSD: src/sys/powerpc/powerpc/bcopy.c,v 1.5.24.1 2010/02/10 00:26:20 kensmith Exp $ */

#include "string.h"

/*
 * sizeof(word) MUST BE A POWER OF TWO
 * SO THAT wmask BELOW IS ALL ONES
 */
typedef    int	word;		/* "word" used for optimal copy speed */

#define    wsize	sizeof(word)
#define wmask    (wsize - 1)

/*
 * Copy a block of memory, handling overlap.
 * This is the routine that actually implements
 * (the portable versions of) bcopy, memcpy, and memmove.
 */
void *memcpy(void *dst0, const void *src0, size_t length)
{
    char		*dst;
    const char	*src;
    size_t		t;

    dst = dst0;
    src = src0;

    if (length == 0 || dst == src) {	/* nothing to do */
    	goto done;
    }

    /*
     * Macros: loop-t-times; and loop-t-times, t>0
     */
#define    TLOOP(s) if (t) TLOOP1(s)
#define    TLOOP1(s) do { s; } while (--t)

    if ((unsigned long)dst < (unsigned long)src) {
    	/*
    	 * Copy forward.
    	 */
    	t = (int)src;	/* only need low bits */

    	if ((t | (int)dst) & wmask) {
    		/*
    		 * Try to align operands.  This cannot be done
    		 * unless the low bits match.
    		 */
    		if ((t ^ (int)dst) & wmask || length < wsize) {
    			t = length;
    		} else {
    			t = wsize - (t & wmask);
    		}

    		length -= t;
    		TLOOP1(*dst++ = *src++);
    	}
    	/*
    	 * Copy whole words, then mop up any trailing bytes.
    	 */
    	t = length / wsize;
    	TLOOP(*(word *)dst = *(const word *)src; src += wsize;
    	    dst += wsize);
    	t = length & wmask;
    	TLOOP(*dst++ = *src++);
    } else {
    	/*
    	 * Copy backwards.  Otherwise essentially the same.
    	 * Alignment works as before, except that it takes
    	 * (t&wmask) bytes to align, not wsize-(t&wmask).
    	 */
    	src += length;
    	dst += length;
    	t = (int)src;

    	if ((t | (int)dst) & wmask) {
    		if ((t ^ (int)dst) & wmask || length <= wsize) {
    			t = length;
    		} else {
    			t &= wmask;
    		}

    		length -= t;
    		TLOOP1(*--dst = *--src);
    	}
    	t = length / wsize;
    	TLOOP(src -= wsize; dst -= wsize;
    	    *(word *)dst = *(const word *)src);
    	t = length & wmask;
    	TLOOP(*--dst = *--src);
    }
done:
    return (dst0);
}
